Homogenizing apparatus of the type disclosed in U.S. Pat. Nos. 2,882,025 and 4,383,769 are employed in the dairy industry to break down and disperse milk fat globules. These homogenizers include a stacked configuration of valve members each of which has an annular knife edge valve seat spaced from an opposing valve surface, to thereby form a narrow gap or slot, through which the milk to be homogenized is forced, whereby the emulsion undergoes extremely rapid acceleration as well as an extreme drop in pressure. The cavitation and turbulence through the valve members breaks down the milk fat globules within the emulsion to produce the homogenized milk. The size of the gap can be varied by a hydraulic actuator acting on the valve stack.
While these known homogenizers have been satisfactory for their intended purpose, they have been characterized by certain disadvantages. For instance, the material from which the valve members have been made is of a hard metal which resists flexing of the valve members during operation, resulting in a cracking of the valve members. Furthermore, the constructural configuration of the valve members included holes formed therein for the flow of the homogenized milk after it had passed through the valve slot or gap. These holes in the valve members further weakened the valve members which contributed to the cracking of the valve members.
Furthermore, the U.S. Food and Drug Administration has set certain standards with regard to the construction and arrangement of milk homogenizers to prevent contamination of the milk during the homogenizing process and to facilitate the washing and cleaning of the homogenizers. For instance, the hydraulic valve actuator has to be spaced from the stacked valve housing so that any hydraulic leakage will flow outside the valve housing to prevent contamination of the milk.
To facilitate washing, all milk contacting surfaces which have angles less than 135.degree. must have a radii in the corner of the angle. Also, there can be no threaded connections within the stacked disc valve housing because threads provide crevices which are very difficult to clean.
To overcome the disadvantages experienced in the prior art homogenizers, the homogenizer of the present invention has been devised and comprises, essentially, a stack of disc valves each of which is made of stainless steel having a Brinell hardness from 40 to 42, and having an annular knife edge spaced from an opposing valve disc, to thereby form a narrow gap or slot, through which the milk to be homogenized is forced.
The stack of disc valves are supported on a bottom plate having stainless steel guide rods welded thereto. The guide rods extend upwardly through the stack of valve discs and through a top plate positioned on the top of the stack of disc valves.
A push rod engages the top plate and is detachably connected to the piston rod of a hydraulic cylinder spaced above the stacked valve housing, the space between the valve housing and hydraulic cylinder communicating with the atmosphere, whereby any leakage from the hydraulic cylinder will not contaminate the milk within the valve housing.